INTRODUCTION TO PHARMACOGNOSY

DR JOSEPH ADUSEI SARKODIE

DEFINITION

The term Pharmacognosy has been derived from the 

2 Greek words:

 i) pharmakon, which means a drug &

 ii) gnosis, which means knowledge of  or gignosco,

which means to acquire knowledge of.

 Thus the full meaning of the term Pharmacognosy is

`knowledge of drugs’ or `to acquire knowledge of

drugs’.

WHAT IS PHARMACOGNOSY? Is the study of Physical, Chemical,

Biochemical and Biological properties of drugs or substances from natural origin

PHYSICAL

Form Odour Colour pH Melting point Solubility

CHEMICAL

Isolation-CC

Composition

Identification

BIOCHEMICAL

Characterisation-methods used to characterise the chemical bonds present

NMR HPLC MS

BIOLOGICAL

Pharmacology Beneficial Adverse effect of substance

Pharmacognosy is one of the main disciplines in pharmacy

Others include:Pharm. ChemPharmaceutics and MicrobiologyPharmacologyClinical and Social pharmacy

INTRODUCTION TO PHARMACOGNOSY

Pharmacognosy is an applied science which is concerned with acquiring knowledge of crude drugs by the application of various scientific disciplines

Pharmacognosy deals with NATURAL products and is described as:

the study of medicinal or therapeutic agents of natural origin, i.e.

Plants Animals Mineral sources It also includes the study of their history,

distribution, cultivation, collection, preparation, identification, evaluation, preservation & commerce

ORIGINS AND HISTORY OF PHARMACOGNOSY

Pharmacognosy is regarded as the mother of all sciences

History of Pharmacognosy represents the history of pharmacy and medicine.

Pharmacognosy had its origin in the health related activities of the most primitive human race of the remote past. 

The early man sought to alleviate his sufferings of illness and injuries by using plants.

Studies of the use of medicinal plants is pre-historic

Discovery of the medicinal properties of plants and other natural products started in the very early days of man’s existence.

METHODS USED

Trial and error Observation of animal instinct on plants Divination By superficial resemblance between the plant

parts & the affected organs, that is, by examining the

“Signature of Nature” By accidental discovery

These contributed to the acquisition on knowledge and conservation of the medicinal properties of natural products

Such pieces of information laid the foundation for medicine.

HISTORY OF NATURAL PRODUCTS IN MEDICINE

Records of medicinal properties of plants dates back to creation

Ezekiel 47:12 Earliest known medical document is a 4000-year-

old Sumerian clay tablet that recorded plant remedies for various illnesses (6th-2nd millennium B.C.)

Papyrus Ebers from Egypt (1550 B.C.)

EGYPTIANS (EBERS PAPYRUS, 1550 BC)

Other documented history is that of the use of Chaulmoogra oil form spp of Hydnocarpus, which was known to be effective in the treatment of leprosy.

Recorded in the pharmacopoeia of the Emperor Shen Nung of China between 2730 B.C. and 3000B.C

Biblical references.

AUTHORS OF ANTIQUITYHIPPOCRATES (460-377 BC)

“THE FATHER OF MEDICINE”(400 HERBAL REMEDIES)

THEOPHRASTUS (370-287 B.C.)HISTORIA PLANTARUM

PEDANIUS DIOSCORIDES (40-80 AD)“DE MATERIA MEDICA” (600 MEDICINAL PLANTS)

Galen (130-201 A.D.)Introduced dosage forms and standardised dosages.

Dale’s Pharmacologia separated Therapy from Preparation of drugs. Which led to founding of Medicine and Pharmacy as two separate professions.

PHARMACOGNOSY

This term was introduced by C.A. Seydler, a German medical student in 1815.

Pharmakon- drug/medicine gnosis- knowledge gignosis- to acquire knowledge Pharmacognosy therefore means

knowledge of drugs.

Alexander Tschirch (1856- 1939), regarded as one of the founders of Modern Pharmacognosy.

Defined Pharmacognosy as the science whose object is to study scientifically drugs of plant and animal origin from every view point with the exception of their physiological action.

Pharmacognosy relates largely to botany and organic chemistry and covers Origin of plant drugs Source and distribution- Botanical and

Geographical sources Cultivation Collection and Preparation for the market Identification- Botanical and chemical Constituents Use of plant drugs

CONSTITUENTS OF MEDICINAL PLANTS

Plants contain chemical compounds Some of these compounds are responsible

for the effectiveness of the plants as medicinal agents

these compounds are described as CONSTITUENTS

IMPORTANCE /ROLES OF PLANT CONSTITUENTS

1. Some take on characteristic histological features useful for plant identification

2. Produce characteristic colours with reagents (useful for identification)

3. Influence factors for preparing plant drugs for the market

4. Time and temperature for drying (E.g. cardiac glycosides and essential oils)

5. Storage conditions (E.g. Cascara increases in medicinal vale with long storage)

6. Useful in biosynthetic studies7. Important for pharmacological and

therapeutic activity8. Useful as excipients and flavouring agents

TYPES OF CONSTITUENTS

These range from simple compounds, e.g. sugars, amino acids to complex molecules, e.g.Steriods and Vitamins

1. Active constituents- those that are responsible for activity, E.g. tannins and alkaloids

2. Inactive/inert constituents- these are present in the plants but do not produce any therapeutic activity. E.g. lignin, cellulose and suberin

FORMATION OF CONSTITUENTS Simple compounds, e.g. sugars, amino acids, fatty

acids, plant acids are produced as a result of the plant’s basic metabolism

Products obtained are referred to as PRIMARY PLANT METABOLITES.

These give rise to more complex products called SECONDARY PLANT METABOLITES, through biological and biochemical processes called BIOSYNTHESIS or BIOGENESIS

Most active plant constituents are secondary plant metabolites

CLASSES OF CONSTITUENTS COMMONLY ENCOUNTERED

Carbohydrates Compounds made up of C, H, O as polyhydroxy

aldehyde or ketone alcohols, with H and O usually present in ratio 2:1.

May be divided into; 1. SUGARS, e.g. glucose, sucrose, etc2. NON-SUGARS, e.g. Starch, cellulose, gums

Glycosides Compounds which on hydrolysis breakdown

into: A SUGAR portion And NON-SUGAR portion called AGLYCONE There are various classes of glycosides

including Cyanogenetic glycosides- yield HCN on

hydrolysis Anthraquinone glycosides Cardiac glycosides- have activity on heart

muscles Saponin glycosides- froth forming

Tannins

Lipids Esters of long chain fatty acids and alcohols Include fixed oils, fats and waxes

Volatile/essential oils Odoriferous principles found in plants Volatile in steam and Made up of terpene derivatives

Alkaloids Nitrogenous compounds usually heterocyclic,

basic character with pharmacological activity

Steroids Derivatives of cyclopentanophenanthrene

skeleton

TERMINOLOGIES

Preparations Decoction: A tea made from boiling plant

material, usually the bark, rhizome, roots in water.

Infusion: A tea made by pouring water over plant material (usually dried flowers and leaves, though fresh material may also be used), then allowed to steep. The water is usually boiling, but cold infusions are also an option.

Tincture: An extract of a plant made by soaking herbs in a dark place with a desired amount of either alcohol or vinegar for a period of time. The liquid is strained from the plant material and then used therapeutically.

Poultice: A therapeutic topical application of a soft moist mass of plant material (such as bruised fresh herbs) on the skin

Medicinal plant: Any plant which in whole or part contains substances that can be used for therapeutic purposes or which are precursors for the synthesis of useful drugs.

Herbal medicine: The study or use of medicinal plants to prevent and treat diseases and ailments or to promote health and healing OR A drug or preparation made from a plant or plants and used for any of such purposes

MEDICAL TERMINOLOGIES

Abortifacient- Inducing abortion Adjuvant- aiding the action of a

medicinal agent Analgesic- relieve pain Anesthetic- induces loss of sensation

or consciousness due to the depression of nerve function

MEDICAL TERMINOLOGIES

Antifungal- destroying or inhibiting the growth of fungus

Antihemorrhagic- controlling hemorrhaging or bleeding.

Aperient- a very mild laxative Aperitive- stimulating the appetite for food Aphrodisiac- substance increasing the

capacity for sexual arousal Astringent- substance is a chemical

compound that tends to shrink or constrict body tissues, usually locally after topical medicinal application

MEDICAL TERMINOLOGIES

Antipruritic- preventing or relieving itching Antipyretic- agent that reduces fever Antispasmodic- calming nervous and

muscular spasms or convulsions Antitussive- controlling or preventing cough